JoWUA

Abstract

LoRa can be used as the communication technology for the intelligent monitoring system. However, LoRa is usually used for outdoor communication. The usage of LoRa as indoor communication has many challenges. One of the challenges is that collision happens when using standard LoRa devices with only one channel. The algorithms based on TDMA (Time-division Multiple Access) and CSMA (Carrier-sense Multiple Access) protocols can be used to address this challenge. These two algorithms can be modified by applying the device that is the center of the network (gateway) as a central control and the data transmitter (sensor node) as a passive device. The test was conducted on the Intelligent Laboratory Monitoring System to evaluate this design on a multinode LoRa network. RSSI testing proves that the distance and building interference affect the signal strength or RSSI of sensor nodes so that the RSSI value is -79.5 for Node1, -86 for Node2, -44.5 for Node3, and -85 for Node4 with an RSSI threshold of value -106. The gateway successfully collected Each sensor node data with a percentage of 70.326% for Node1, 95.751% for Node2, 42.267% for Node3, and 51.468% for Node4. The results of the algorithm comparison test prove that the CSMA algorithm with a success rate of 10% versus 100% in TDMA will be more prone to collisions; CSMA takes 4125 ms to collect data from a single sensor node compared to TDMA, which only takes 428.3 ms; CSMA has more flexible scheduling; and CSMA has a more complex mechanism than TDMA.